High strength banding tape



Jan. 15, 1963 c. L. zElsE, JR 3,073,004

HIGH STRENGTH BANDING TAPE Filed Aug. 31, 1959 y 2e T20 Fig.3

wlTNEssEs Y mvENToR Clarence L. Zeise, Jr.

ATTORNEY atent Office Patented dan. l5, 1953 3,073,004 HIGH STRENGTHBANDING TAPE Clarence L. Zeise, Jr., Plum Boro, Pa., assignor toWestinghouse Electric Corporation, East Pittsburgh, Pa., a corporationof Pennsylvania Filed Aug. 31, 1959, Ser. No. 836,963 3 Claims. (Cl.28-80) This invention relates to tapes and particularly to flexible,tack-free tapes having high tensile strength.

This invention is directed to banding tapes of high tensile strength,which tapes comprise a fabric composed of a plurality of glass warpyarns which extend longitudinally of the tape and soft, non-abrasivefill yarns and a potentially thermosettable resinous compositionimpregnating and coating the fabric. The banding tapes of this inventionhave particular application for the banding of armatures and likemembers. The tapes can also be ernployed for other applicationsrequiring high strength band members.

For a full and complete understanding of the nature of this invention,reference is made to the following detailed description and drawing, inwhich:

FIG. 1 is a lfragmentary perspective view of fabric suitable for use inthis invention;

FIG. 2 is a cross-sectional view showing the fabric of FIG. 1 havingapplied thereto a potentially thermosettable resinous composition; and,

FIG. 3 is a fragmentary longitudinal sectional view of a portion of adirect current dynamo-electric machine showing a band member applied onone end of the armature.

In accordance with this invention there is prepared a high strength tapehaving a tensile strength within the range of at least 800 to 1500pounds per inch, which tape is highly suitable for the banding ofarmatures and like members. The tape of this invention comprises afabric composed of a plurality of closely packed continuous filamentglass warp yarns which extend longitudinally of the tape and spaced fillyarns of a relatively soft, nonabrasive yarn disposed at anglessubstantially perpendicular with respect to the glass warp yarns, and apotentially thermosettable resinous composition impregnating and/orcoating the fabric to provide a resin ratio of from about 1.10 to 1.50.The preferred resin ratio being within the relatively narrow range offrom 1.15 to 1.30.

Resin ratio is defined as the ratio of the weight of the untreated sheetof fabric plus the weight of the resin that is applied to the sheet tothe weight of the untreated sheet.

The glass warp yarns that extend longitudinally of the .tape areprepared from continuous filament glass yarns for ultimate tensilestrength properties. The glass yarns are' closely packed and the numberof warp yarns per inch is preferably with the range of from about 60 toThe lill yarns are preferably widely spaced and can be employed in theamount of from about 1 to 20 yarns from polymers of acrylonitrile, such`as those available commercially under the proprietary names Orlon andAcrilan; copolymers of vinyl chloride and acrylonitrile, availablecommercially under the proprietary name Dynel; polyethyleneterephthalate, available commercialF ly under the proprietary nameDaeron; high molecular weight linear polyamides, available commerciallyunderv the name nylon; copolymers of vinyl chloride and vinylidenechloride available commercially under the proprietary name Saran; andcopolymers of vinyl chloride and vinyl acetate, available commerciallyunder the proprietary name Vinyon. Fill yarns comprising variouscombinations of the above iibers can be employed.

The tapes of this invention may be prepared from sheet material of asubstantial width, for example, from about 36 inches to 40 inches orthey may be prepared from fabric already cut into the desired tapewidth, for example 5% inch to 2 inches. If sheet material of substantialwidth is employed, it is, after resin treatment, slit into tapes ofdesired width.

The characteristics of a highly suitable glass fabric, in sheet or tapeform, that can be employed in this invention are set forth in Table Ibelow.

TABLE I Weave Unidirectional. Weight, ounce per square yard 9.7. Glasswarp yarn (continuous filament) 1 l50-2/ 2. Warp yarn per inch Fillyarn, Daeron (continuous lament) 70 denier.

Fill yarns per inch 14.

1 150-2/2 means that two ends of 150 untwisted yarns are broughttogether, and then two of these -2 end yarns are piled together; theexpression 150 means 15,000 yarns to the pound.

Referring to FIG. 1 of the drawing, there is shown fabric 10 which is aunidirectional weave made by interleaving yarns 12 of continuous glasslament fibers with ll yarns 14 of smaller diameter. The yarns 14 aremore widely spaced than the Warp yarns 12, which are closely packed.

A single continuous filament of about 70 denier and prepared from one ofthe synthetic organic materials hereinbefore described has proved highlysatisfactory in preparing the unidirectional fabric for use in thisinvention. The fill yarns are of substantially smaller diameter, usuallyof the order of from about 60 to 120 denier, than the warp yarns and arespaced apart relatively widely. A fabric constructed in this manner andas shown in FIG. 1 has little tensile strength in a ldirection generallytransverse to the direction of the warp yarns 12, and extremely hightensile strength in the direction of the glass warp yarns 12. Therelatively small diameter of the till yarns 14 and the relatively widespacing thereof prevents sharp bends in the glass liber yarns 12 so thatthe glass fiber yarns 12 are arranged in a relatively straight line. Inthis relation the warp yarns are in the best position to bear hightensile stresses.

The unidirectional fabric is impregnated and/ or coated with the desiredresinous composition, preferably by dipping a sheet or tape of thefabric in a bath containing the resinous composition dissolved in asuitable solvent. After this impregnation and/or coating of the fabric,the treated fabric is dried to remove the solvents therefrom and toprovide a treated sheet material that is flexible and tack-free. It maybe then stored for future use or used immediately. Sheets of fabric aresubsequently slit into tapes of desired width.

it is important that the resin or resin composition employed in treatingthe fabric of this invention be such that a tack-free resin coating isprovided on the surface of the treated fabric. t is apparent that atack-free treated tape is highly desirable for ease of application andfurthermore, a tack-free condition prevents dirt and other deleteriousmaterial from adhering to the tape during application thereof.

FIG. 2 of the drawing is a cross section of the glass fabric 10impregnated and coated with a potentially thermosettable resinouscomposition 16.

There are many heat-hardenable resins and resin compositions that may beemployed in treating the fabric to produce the bandin. tape of thisinvention. Thermoplastic resinous compositions are not desirable becausethey will soften at relatively low temperatures. The banding tapes ofthis invention will ordinarily be employed in apparatus that Will besubjected to high ternperatures in service. Thus it is preferred toemploy thermosettable resinous compositions.

Numerous thermosettable resinous compositions are available. Phenolicresins, polyepoxides, melamine-aldehydc resins, and silicone resins, forexample, may be employed.

Exceptionaliy good results have been secured with completely reactivepolyester-type resinous compositions that thermoset. These completelyreactive compositions may comprise one or more compounds containing twoor more unsaturated aliphatic groups. Examples of such compounds arediallyl phthalate, diallyl sebacate, and divinyl benzene. The liquidresinous compositions to be used may employ two or more compounds havingreactive unsaturated C=C groups capable of vinyl-type additionpolymerization. Particularly good results have been secured byemployinga solution comprising a liquid monomeric compound having the group H2C=Cin which is dissolved an unsaturated polyester having the group C=CvParticularly good results have been secured by employing7 as apolyester resin the reaction product of an ethylenic dicarboxylic acidor anhydride thereof such, for example, asV maleic acid, umaric acid,maleic anhydride, monochlormaleic acid, itaconic acid, itaconicanhydride, citraconic acid and citraconic anhydride. The unsaturateddicarboxylic acid or anhydride or mixtures thereof are reacted with asubstantially molar equivalent of one or more polyhydric alcohols suchas ethylene glycol, glycerol, propylene glycol, diethylene glycol,pentaerythritol or mixtures of two or more. Castor oil has been employedsuccessfully in an esteriiication reaction with maleic anhydride. Theresultant ester, such as castor oil maleate ester, is admixed with apolymerizable unsaturated monomer, for example, monostyrene, in theproportions of from about l to 95 parts by Weight of the monostyrene andfrom 90 to 5 parts by weight of the ester.

inthe preparation of the unsaturated alkyd esters, an ethylenicallyunsaturated alpha-beta dicarboxylic acid or anhydride thereof may bereplaced with up to 95% of the weight thereof by a saturated aliphaticdicarboxylic acid or aryl dicarboxylic acid or anhydride, such forexample as succinic acid, adipic acid, sebacic acid, phthalic acid,phthalic anhydride or the like. In some instances, epoxides have beenemployed in lieu of glycols, particularly in reaction with dicarboxylicacid instead of their anhydrides.

The unsaturated alkyd esters are dissolved in a liquid unsaturatedmonomer having the group H2C=C Suitable liquid Vunsaturf'itedpolymerizable monomers are: monostyrene, alpha-methylstyrene,2,4-dichlorostyrene, paramethyl styrene, vinyl acetate, methylmethacrylate, ethyl acrylate, diallyl phthalate, diallyl succinate,diallyl mal'eate, allyl alcohol, methallyl alcohol, acrylonitrile,methyl vinyl ketone, diallyl ether, vinylidene chloride, butylmethacrylate, allyl acrylate, allyl crotonate, 1,3- chloroprene, anddivinyl benzene, as well as mixtures of two or more of any of thesemonomers. Y

An excellent completely reactive composition is one composed Vof asolution of from 90 to 50 parts of arylalkene polymerizable monomer offrom 10 to 50 parts by weight of the alkyd reaction product of (A) anunsaturated acidic compound from the group consisting of maleic acid,maleic anhydride, fumarie acid, citraconc acid, and citraconic anhydrideVin admixture with one or more saturated straight chain dicarboxylicacids having the carboxyl groups disposed at the end of the straightchain, the chainy having from 2 to l0 non-carboxyl cari bon atoms and noother reactive groups, and (B) a molar equivalent within il0% of analiphatic saturated glycol having no other reactive groups than thehydroxyl groups. The proportion of the unsaturated acidic compound inthe mixture ot acids should be between 5% and 50% ofv the weight of themixture. Suitable saturated dicarbox ylic acids are adipic acid, sebacicacid, azelaic acid, suberic acid, succinic acid, decamethylenedicarboxylic acid and diglycolic acid and mixtures thereof. With thelonger chain saturated dicarboxylic acids as, for example sebacic acid,the proportion of maleic anhydride, for example, may be higher than ifthe saturated acid were all succinic acid, if cured products of similardegrees of hardness are desired. Suitable glycols for reaction with themixture of saturated and unsaturated acids are ethylene glycol,propylene glycol, diethylene glycol, 1,5- pentanediol and triethyleneglycol. Mixtures of the glycols are suitable for producing the reactionproduct. The reaction of the (A) acidic compounds and (B) the glycolscan be carried out by heating in a reaction vessel at temperatures offrom 100 C. to 250 C. for from 24 hours to 2 hours to a low acid numberof below 60.

The following are speciiic examples of the preparation ol theunsaturated alkyd reaction products to be dissolved in a vinyl arylmonomer:

Example I A mixture ot 4,4 mole percent of adipic acid and 6 molepercent of fumaric acid are combined with '50 mole percent of propyleneglycol and reacted with CO2 sparging for about 4 hours at 140 C. in aclosed reaction vessel after which the temperature is raised to about220 C. over a 4 hour period and the reaction is continued at 220 C. for8 hours. A syrupy polyester resin is produced.

Example II Another composition comprises the reaction product of l0 molepercent of maleic anhydride, 40 mole percent of adipic acid, and 50 molepercent of diethylene glycol.

Example III A reaction product is prepared by reacting 30 mole percentof sebacc acid, 20 mole percent of maleic anhydride, and 50 mole percentof diethylene glycol under the same conditions as in Example I with asyrupy resin of low acid number resulting.

The unsaturated esters of alkyd resins of these examples are dissolvedin a monomeric compound having the group H2C,=C such as monostyrene, ora simple substitution derivative of monostyrene, or a mixture of two ormore monomers, as above described, to produce low viscosity completelyreactive solutions having present from 15% to by weight of theunsaturated ester. Particularly good results are obtained by dissolvingthe unsaturated esters in monostyrene to produce solutions containingfrom 20% to 85% by weight of monostyrene and the balance, 80% to 15% byweight, composed of the unsaturated esters.

The above solutions are solvent reactive compositions which willpolymerize completely when admixed with one or more vinyl-typepolymerization catalysts, such as benzoyl peroxide, lauroyl peroxide,methyl ethyl ketone peroxide, t-butyl hydroperoxide, ascaridole, t-butylperbenzoate, di-t-butyl diperphthalate, ozonides, and similar catalysts,lin an amount of from 0.5% to 5% and more, by weight. A proportion ofthe catalyst obviously may be present in amounts differing from thesepercentages.

Example IV The resin composition of Example III is dissolved inmonostyrene to producel a solution composed of 35% by weight ofmonostyrene and 65% by weight of the polyo varnish impregnatingcomposition composed of about 50% resin solids.

Other suitable solvents that may be employed for dissolving the resinpolyester compositions described above are benzene, xylene, ethanol,isopropanol, and methyl ethyl ketone.

The resinous varnish composition of Example IV is employed to impregnateand coat a sheet of fabric having the construction as set forth in TableI to a resin ratio of abolt 1.20. The impregnated sheet is passed intoan oven to remove the solvent, to advance the cure of the resincomposition to the B-stage, and to provide a tack-free, exible sheet offabric composed of the glass fabric of Table I and the polyester resincomposition of Example III.

The treated sheet is slit to one inch widths to provide tack-free,liexible banding tapes. One of the banding tapes is wrapped around a 6inch diameter mandrel to provide thereon a convolutely wound band orhoop having a wall thickness of about 1 inch. The wrapped mandrel isplaced in an oven for 30 minutes at a temperature of about 160 C.,removed from the oven and cooled to room temperature. The band thusproduced is removed from the mandrel and tested for tensile strength andthe resulting test indicated that the hoops would withstand a load of29,900 pounds and had an ultimate tensile strength of 96,800 pounds persquare inch. The tensile tests were performed on a Baldwin Southwarkuniversal testing machine.

Referring now to FIG. 3 of the drawing, there is illustrated theapplication of the banding tape of this invention to an armature orrotor member 20 of a direct dynamo-electric machine which also has afield-member or stator member 22. As shown, an armature band or bandmember 24 has been applied about the periphery of coil ends or end turns26 of the armature winding to retain the winding against centrifugalforce. A desired number of layers of the flexible, tack-free tape ofthis invention is wound tightly around coil ends 26. Heat is applied tocure the resin composition comprising the tape to an infusible,insoluble state to produce `armature band 24.

It is well known in the art that it is necessary to provide a band aboutthe winding end turns of a rotor, armature and like rotating members ofelectro-dynamic machines to prevent the end turns from moving radiallyoutwardly under the action of centrifugal force.

In the particular case illustrated, the armature band 24 is used to holdend turns 26 against coil support Z8. It is intended that the abovedescription and drawing are merely descriptive of the invention and notin limitation thereof.

I claim as my invention:

1. A iiexible banding tape comprising a fabric coinprised of from to 100closely packed continuous lilament glass warp yarns per inch which warpyarns extend longitudinally of the tape and from 1 to 20 spacedcontinuous organic filament till yarns per inch, and a potentiallythermosettable resin composition selected from at least one of the groupconsisting of polyepoxide resins, polyester resins, phenolic resins andsilicone resins impregnating and coating the fabric to provide a resinratio of from about 1.10 to 1.50, said tape being tack-free and having atensile strength within the range of from at least 800 to 1500 poundsper inch.

2. A exible banding tape comprising a fabric comprised of from 60 to 100closely packed continuous tilament glass warp yarns per inch which warpyarns extend longitudinally of the tape and from 8 to 18 spacedcontinuous organic filament non-abrasive till yarns per inch, and apotentially thermosettable resin composition selected from at least oneof the group consisting of polyepoxide resins, polyester resins,phenolic resins, and silicone resins irnpregnating and coating thefabric to provide a resin ratio of from about 1.15 to 1.30, said tapebeing tack-free and having a tensile strength within the range of fromat least 800 to 1500 pounds per inch.

3. A flexible tack-free banding tape comprising a fabric comprised offrom 60 to 100 closely packed continuous ilament glass warp yarns perinch which warp yarns extend longitudinally of the tape and from 8 to 18spaced continuous organic filament non-abrasive iill yarns per inch, anda potentially thermosettable polyester resin composition impregnatingand coating the fabric to provide a resin ratio of from about 1.15 to1.30, said tape having a tensile strength within the range of from atleast 800 to 1500 pounds per inch.

References Cited in the file of this patent UNITED STATES PATENTS2,372,983 Richardson Apr. 3, 1945 2,477,407 Grant et al July 26, 19492,562,951 Rose et al. Aug. 7, 1951 2,896,100 Axelson July 21, 1959BANDING 18, 1969, by the assigne Hereby dedcates the jfoz'al GazetteDedication Plum Bo tent dated J an. e, Westz'ngo manng term of etoberI4, 1.969.]

ro, Pa

use Electric 00 the patent to th HIGH STRENG 15,1903-Ded' rpomtz'on,

e Public.

Dedication 3,073,004.-0Zareme L. Zeige, Jr., Plum Boro, Pa. HIGHSTRENGTH BANDING TAPE. Patent dated J an. 15, 1963. Dedication filedJune 18, 1969, by the assignee, Westinghouse Electric Uowpomzfon.

Hereby dedicates the remaining term of the patent to the Public.

[Oficial Gazette October 14, 1969.]

1. A FLEXIBLE BANDING TAPE COMPRISING A FABRIC COMPRISED OF FROM 60 TO 100 CLOSELY PACKED CONTINUOUS FILAMENT GLASS WARP YARNS PER INCH WHICH WARP YARNS EXTEND LONGITUDINALLY OF THE TAPE AND FROM 1 TO 20 SPACED CONTINUOUS ORGANIC FILAMENT FILL YARNS PER INCH, AND A POTENTIALLY THERMOSETTABLE RESIN COMPOSITION SELECTED FROM AT LEAST ONE OF THE GROUP CONSISTING OF POLYEPOXIDE RESINS, POLYESTER RESINS, PHENOLIC RESINS AND SILICONE RESINS IMPREGNATING AND COATING THE FABRIC TO PROVIDE A RESIN RATIO OF FROM ABOUT 1.10 TO 1.50, SAID TAPE BEING TACK-FREE AND HAVING A TENSILE STRENGTH WITHIN THE RANGE OF FROM AT LEAST 800 TO 1500 POUNDS PER INCH. 